Chronic lymphocytic leukemia (CLL) is the most common type of leukemia among Western countries. There are about 191,000 cases of CLL diagnosed per year worldwide.

Read on to learn how CLL is diagnosed and staged, and what the outlook is if you or someone you care for has this blood cancer.

CLL is a slow-growing leukemia that affects white blood cells (WBCs) known as lymphocytes.

With CLL, your body makes abnormal (aberrant) lymphocytes that interfere with the normal functioning of healthy lymphocytes. This makes it harder for the healthy lymphocytes to protect you against illnesses.

CLL cells can compromise your immune system and reduce the amount of red blood cells (RBCs) and platelets you produce.

Most patients have few or no symptoms when they are first diagnosed with CLL. An oncologist or other healthcare professional may suspect CLL when the results of a routine blood test come back abnormal.

In this case, you will undergo further exams and tests to pinpoint the cause of your results.

Physical exam

At the start of your visit, a healthcare professional will ask about any symptoms you’re having, including when they started, how often they occur, and how intense they are.

They will also ask about your individual and family medical history and risk factors related to CLL.

The healthcare professional will then look, listen, and feel for signs that point to CLL during your exam — the most common being swollen lymph nodes in your neck, armpit, or groin. CLL cells can be found in your spleen and liver.

Less common symptoms may include:

Blood tests

Blood tests are often the first tests to be performed and are usually enough to diagnose CLL. These tests may include the following types.

Complete blood count with differential

A complete blood count with differential measures the various blood cell types in your body, such as red blood cells (RBCs), WBCs, and platelets. It also detects the amount of each type of WBC you have.

If your results show lymphocytosis, or the presence of too many lymphocytes (more than 10,000 per mm³), this may suggest CLL. Your RBC and platelet counts may also be lower than usual.

Flow cytometry

Flow cytometry is a lab test that uses a special machine to confirm your CLL diagnosis. It finds, identifies, and counts CLL cells by searching for key markers within cells or on their surface.

Bone marrow testing

A bone marrow test may be used to evaluate whether you have cytopenia. It can also help determine how far your cancer has progressed.

During a bone marrow aspiration, a needle is inserted into the back of your hip bone to collect bone marrow samples.

A bone marrow biopsy will be performed shortly after aspiration.

If you have CLL, the results of your bone marrow test may show:

  • marrow with too many cells that form blood
  • the number of normal cells within your bone marrow that have been replaced by CLL cells
  • the CLL spread pattern in your marrow, which can either be:
    • nodular or interstitial (small clusters of cells), which may suggest a better outlook
    • diffuse or scattered, which can lead to a poorer prognosis

Imaging tests

CT and PET-CT scans

A CT scan may show swollen lymph nodes, liver, and spleen.

A PET scan may be performed with your CT in a combined test called a PET-CT scan.

A PET-CT may indicate cancer growth or spread as shown by areas of radioactive glucose that are readily absorbed by CLL cells. PET scans can also provide greater image detail of the scanned area on your CT.


An ultrasound can be used to see if your liver, spleen, or lymph nodes are enlarged.

Genetic and molecular tests

These tests look at changes in certain chromosomes or genes. In some cases, parts of chromosomes may be missing or deleted.

Deletions in parts of chromosomes 11 and 17 may point toward a poorer outlook and shorter survival times. On the other hand, when parts of chromosome 13 are missing, this type of disease is linked to better outcomes and longer survival times.

These types of testing may include:

CLL staging helps determine when to start treatment and when it should be delayed with close monitoring.

Rai staging system

In the United States, the Rai staging system is most often used for CLL. It consists of three risk groups:

  • Low risk (stage 0):
    • lymphocytosis
    • no enlarged lymph nodes or organs
    • RBC and platelet counts within or near normal levels
  • Intermediate risk (stages 1 and 2):
    • lymphocytosis
    • enlarged lymph nodes, spleen, or liver
    • RBC and platelet counts within or near normal levels
  • High risk (stages 3 and 4):
    • lymphocytosis
    • enlarged lymph nodes, spleen, or liver may or may not be present
    • anemia, or low RBC count
    • thrombocytopenia, or low platelet count

CLL has a higher survival rate than many other cancers. The 5-year survival rate is around 86 percent. This means that 86 percent of people with the condition are alive 5 years after diagnosis. However, in those over age 75, the 5-year survival rate drops to less than 70 percent.

The median survival rate for CLL is 10 years, but it can range from 2 to 20 years or more. You may survive with no treatment for 5 to 20 years if you are in Rai stages 0 to 2.

Staging and other factors such as age, gender, chromosome abnormalities, and traits of your CLL cells can impact your specific outlook.

Lymphocyte doubling time (LDT) is the number of months needed for your lymphocyte count to double. CLL tends to be more aggressive in people with an LDT of less than a year.

A tool commonly used to predict CLL outcomes is the International Prognostic Index for Chronic Lymphocytic Leukemia (CLL-IPI). CLL-IPI looks at age and genetic, biochemical, and physical findings to determine your outlook.

Other similar diseases that a healthcare provider might investigate or rule out include:

CLL can also morph into more aggressive cancers such as diffuse large B cell lymphoma or Hodgkin’s disease.

CLL is a blood cancer that affects your white blood cells. After a physical exam, blood tests are often used for diagnosis.

In the United States, the Rai staging system is the most common approach to staging CLL.

Risk factors such as age and chromosome abnormalities can affect your outcome. But because CLL often grows slowly, survival rates can be up to 20 years or more for people in Rai stages 0 to 2.